Observations and properties of candidate high-frequency GPS radio sources in the AT20G survey

Abstract

We used the Australia Telescope Compact Array (ATCA) to obtain 40 and 95 GHz observations of a number of sources that were selected from the ATCA 20 GHz (AT20G) survey. The aim of the observations was to improve the spectral coverage for sources with spectral peaks near 20 GHz or inverted (rising) radio spectra between 8.6 and 20 GHz. We present the radio observations of a sample of 21 such sources along with optical spectra taken from the Australian National University Siding Spring Observatory 2.3-m telescope and the European Southern Observatory New Technology Telescope (NTT). We find that as a group the sources show the same level of variability as typical Gigahertz Peaked Spectrum (GPS) sources, and that of the 21 candidate GPS sources roughly 60 per cent appear to be genuinely young radio galaxies. Three of the 21 sources studied show evidence of being restarted radio galaxies. If these numbers are indicative of the larger population of AT20G radio sources, then as many as 400 genuine GPS sources could be contained within the AT20G with up to 25 per cent of them being restarted radio galaxies. © 2010 The Authors. Journal compilation © 2010 RAS.